A way of organizing & classifying elements • Arranged in rows and columns
Columns • The vertical (up and down) columns of the periodic table (there are 18) are called groups or families. • Elements in the same group or family have similar characteristics or properties.
Rows • The horizontal rows of the periodic table are called periods. • Elements in a period are not alike in properties. • The first element in a period is usually an active solid, and the last element in a period is always an inactive gas.
Rows • Atomic size (number of protons) decreases from left to right across a period. • Atomic mass increases from left to right across a period.
Rows • Metals are on the left • Non-metals are on the right
ALKALI METALS • very reactive metals that do not occur freely in nature • malleable, ductile, good conductors of heat and electricity. • softer than most other metals • can explode if they are exposed to water
ALKLINE EARTH METALS • metals • very reactive • not found free in nature
TRANSITION METALS • ductile and malleable, and conduct electricity and heat • iron, cobalt, and nickel, are the only elements known to produce a magnetic field.
RARE EARTH ELEMENTS • many are man-made
OTHER METALS • are ductile and malleable • are solid, have a relatively high density, and are opaque
METALLOIDS • have properties of both metals and non-metals • some of the metalloids, such as silicon and germanium, are semi-conductors. This means that they can carry an electrical charge under special conditions. This property makes metalloids useful in computers and calculators
NON-METALS • not able to conduct electricity or heat very well • very brittle, and cannot be rolled into wires or pounded into sheets • exist in two of the three states of matter at room temperature: gases (such as oxygen) and solids (such as carbon). • have no metallic luster, and do not reflect light.
HALOGENS • "halogen" means "salt-former" and compounds containing halogens are called "salts" • exist in all three states of matter: • Solid- Iodine, Astatine • Liquid- Bromine • Gas- Fluorine, Chlorine
NOBLE GASES • do not form compounds easily